When new railcars are manufactured, and when a new line is constructed, their safety has to be verified. In addition, since a friction coefficient between a wheel and a rail, and a state of a track are changing with time, a state of a force applied between the wheel and rail changes over time after the new railcars are manufactured or when the new line is opened.
Therefore, the safety has to be verified even in commercial lines.
Examples of running safety evaluating methods for the railcar include a method using a derailment coefficient. The derailment coefficient is a value represented by Q/P, wherein Q is a horizontal force applied between a wheel and a rail, i.e., a lateral force in the direction along an axle, and P is a wheel load that is a vertical force applied between the wheel and the rail. The derailment coefficient becomes one index for evaluating the running safety of the railcar, as indicated by this equation, so that the wheel load (P) and the lateral force (Q) are measured.